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An article on bioRxiv, Evaluation of heating and chemical protocols for inactivating SARS-CoV-2, recommends certain treatments to inactivate SARS-Cov-2 for lab work.

The abstract notes: "Although heating protocol consisting of 92°C-15min was more effective rather than 56°C-30min and 60°C-60min to achieve 6-log reduction, it is not amenable for molecular detection on respiratory specimens because of important decrease of detectable RNA copies in the treated sample vs untreated sample."

Do I understand correctly that 56C/30min is broadly as effective as 60C/60min? Given that 56C from previous research seems to be more effective than 22C, I would have expected 60C to require less time to achieve a similar effect to 56C. Especially with 92C/15min being more effective still, though more disruptive.

I'm curious what the explanation may be why effectivity might drop between 56 and 92C. Or why I may be misunderstanding the temperature/time scales. Please keep it simple. Thank you.

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They only tested 3 heat treatment regimens: 56C/30min, 60C/60min, 92C/15min (6 if you consider the "with BSA" and "without BSA", but only 3 combinations of temperature and time). They didn't measure the time required at certain temperatures to get to a certain level of inactivation. It seems they chose some of these particular protocols because they have been recommended in the past for other viruses.

They don't really have sensitive enough data to compare the 56C/30min to the 60C/60min or really enough to do any sort of statistical comparison whatsoever (as far as I can tell they only tested a single sample of each); yes, you can say they were roughly as effective, but it would be a leap to say 56C is the same as 60C.

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  • $\begingroup$ Thank you. Does anyone know or a have an idea why 60C/60m levels off at an effectiveness comparable to 56C/30m? $\endgroup$ – user345360 Jun 23 at 20:56
  • $\begingroup$ @user345360 In 2 of the tests they ran (one at each temp) they got no detectable virus. In the other one they got a small amount. That's not enough information to make any conclusions about things "leveling off". The temperatures aren't that different, the time isn't that different. At best they might be able to detect a 10-fold change, and even then not be too certain about it. $\endgroup$ – Bryan Krause Jun 23 at 21:05

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